WO2021033267A1 - 電力変換装置 - Google Patents
電力変換装置 Download PDFInfo
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- WO2021033267A1 WO2021033267A1 PCT/JP2019/032466 JP2019032466W WO2021033267A1 WO 2021033267 A1 WO2021033267 A1 WO 2021033267A1 JP 2019032466 W JP2019032466 W JP 2019032466W WO 2021033267 A1 WO2021033267 A1 WO 2021033267A1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0016—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters
- H02M1/0022—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters the disturbance parameters being input voltage fluctuations
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
Definitions
- the present invention relates to a power converter.
- Patent Document 1 Japanese Unexamined Patent Publication No. 2018-207785 (Patent Document 1) includes an inverter that converts a DC voltage into an AC voltage, a transformer provided between the inverter and a load, and a control device that controls the inverter. The converter is disclosed.
- a demagnetization detection circuit is used to detect a DC component included in the output voltage of the inverter, and the waveform of the output voltage of the inverter is controlled so that the detected DC component disappears.
- This demagnetization detection circuit has an integrator that integrates the output voltage of the inverter, and is configured to detect the DC component of the output signal of the integrator.
- an exciting inrush current may be generated in the transformer depending on the phase of the AC voltage at the time of connection.
- the exciting inrush current causes a transient fluctuation in the voltage supplied to the load and may cause the load to malfunction.
- the demagnetization detection circuit described in Patent Document 1 is configured to detect the DC demagnetization of the iron core of the transformer based on the output signal of the integrator and control the inverter, the inverter is used in the transformer. There is a concern that the exciting inrush current that is instantaneously generated when the inverter is connected cannot be suppressed promptly.
- the present invention has been made to solve such a problem, and an object of the present invention is to provide a power conversion device capable of suppressing an exciting inrush current when an inverter is connected to a transformer. That is.
- the power conversion device includes an inverter that converts a DC voltage on the DC side into an AC voltage and outputs the AC voltage, and a control device that controls the inverter.
- the AC side of the inverter is connected to the load via a transformer.
- the transformer is configured to apply an AC voltage output from the AC side to the load.
- the power converter detects the first current detector that detects the primary winding current of the transformer, the second current detector that detects the output current of the inverter, and the AC voltage output from the AC side. Further equipped with a voltage detector.
- the control device includes a voltage control unit, a current control unit, and a PWM circuit.
- the voltage control unit multiplies the detection value of the primary winding current by the first current detector by the gain on the control calculation result for reducing the deviation of the AC voltage detection value by the voltage detector with respect to the AC voltage command value.
- the AC current command value is generated by adding the feed forward term.
- the current control unit generates an inverter control command value by a control calculation for reducing the deviation of the detection value of the output current of the inverter by the second current detector with respect to the AC current command value.
- the PWM circuit PWM-controls the inverter by comparing the inverter control command value with a predetermined carrier wave and generating a control signal of the inverter. When the exciting inrush current is detected in the value detected by the first current detector in the primary winding current, the voltage control unit reduces the gain value as compared with the case where the exciting inrush current is not detected.
- the present invention it is possible to provide a power conversion device capable of suppressing an exciting inrush current when an inverter is connected to a transformer.
- FIG. 1 is a schematic configuration diagram of a power conversion device according to an embodiment.
- a DC power supply 1 is connected to the DC side of the power conversion device 100 according to the embodiment.
- a load 4 is connected to the AC side of the power converter 100 via circuit breakers 2a and 2b and a transformer 3.
- the transformer 3 has a primary winding 3a, a secondary winding 3b and an annular iron core 3c.
- the power conversion device 100 includes an inverter 10, an output filter 12, current detectors 14 and 16, a voltage detector 18, and a control device 20.
- the inverter 10 is controlled by the control signals G1 to G4 supplied from the control device 20, and converts the DC voltage Vb of the DC power supply 1 into an AC voltage Viv.
- the inverter 10 has power semiconductor switching elements (hereinafter, also simply referred to as "switching elements") Q1 to Q4.
- switching elements Each of the switching elements Q1 to Q4 is, for example, an IGBT (Insulated Gate Bipolar Transistor). Both collectors of the switching elements Q1 and Q2 are connected to the positive electrode of the DC power supply 1.
- the collectors of the switching elements Q3 and Q4 are connected to the emitters of the switching elements Q1 and Q2, respectively. Both the emitters of the semiconductor switching elements Q3 and Q4 are connected to the negative electrode of the DC power supply 1.
- IGBT is used as the switching element in FIG. 1, any self-extinguishing type switching element such as MOSFET (Metal Oxide Semiconductor Field Effect Transistor) can be used.
- Diodes D1 to D4 are connected in antiparallel to each of the switching elements Q1 to Q4, respectively. Each of the diodes D1 to D4 is provided to allow freewheel current to flow when the corresponding switching element is off.
- the switching element is a MOSFET
- the freewheel diode is composed of a parasitic diode (body diode).
- the switching element is an IGBT without a built-in diode
- the freewheel diode is composed of diodes connected in antiparallel to the IGBT.
- the switching elements Q1 to Q4 are controlled to be conductive (on) / non-conducting (off) by the control signals G1 to G4 supplied from the control device 20, respectively.
- Each of the control signals G1 to G4 is, for example, a PWM (Pulse Width Modulation) control signal.
- Each cycle of the control signals G1 to G4 is the reciprocal of the switching frequency.
- Each of the control signals G1 to G4 is set to H (logical high) level or L (logical low) level in each cycle.
- Each of the switching elements Q1 to Q4 is turned on when the corresponding control signal is at H level and turned off when the corresponding control signal is at L level.
- the output filter 12 has a reactor L1 and a capacitor C1.
- One terminal of the reactor L1 is connected to the emitter of the switching element Q1.
- the other terminal of the reactor L1 is connected to one terminal of the primary winding 3a of the transformer 3 via the circuit breaker 2a.
- the emitter of the switching element Q2 is connected to the other terminal of the primary winding 3a of the transformer 3 via the circuit breaker 2b.
- the capacitor C1 is connected between one terminal and the other terminal of the primary winding 3a.
- the output filter 12 constitutes a low-pass filter, passes AC power of a desired frequency (for example, a commercial frequency) generated by the switching elements Q1 to Q4, and a signal of the switching frequency generated by the switching elements Q1 to Q4 is transmitted. Prevents it from passing to the load 4 side. In other words, the output filter 12 converts the rectangular wave-shaped AC voltage Vinv generated by turning on / off the switching elements Q1 to Q4 into a sinusoidal AC voltage Vac.
- a desired frequency for example, a commercial frequency
- the transformer 3 supplies the load 4 with an AC voltage Vo corresponding to the AC voltage Vac output from the output filter 12.
- the ratio of the amplitude of the AC voltage Vac to the amplitude of the AC voltage Vo is equal to the ratio N1 / N2 of the number of windings N1 of the primary winding 3a and the number of windings N2 of the secondary winding 3b.
- the load 4 is driven by the AC voltage Vo supplied from the transformer 3.
- the circuit breakers 2a and 2b between the output filter 12 and the transformer 3, the connection and disconnection of the power converter 100 and the transformer 3 can be controlled.
- the current detector 14 detects the reactor current IL of the reactor L1 of the output filter 12.
- the reactor current IL corresponds to the "alternating current” output from the alternating current side of the inverter 10.
- the current detector 16 detects the alternating current Iac output from the output filter 12.
- the alternating current Iac corresponds to the "primary winding current” flowing in the primary winding 3a of the transformer 3.
- the current detector 14 corresponds to an embodiment of the "second current detector”
- the current detector 16 corresponds to an embodiment of the "first current detector”.
- the voltage detector 18 detects the voltage Vac of the capacitor C1 of the output filter 12.
- the voltage Vac of the capacitor C1 corresponds to the "AC voltage” on the AC side of the inverter 10.
- the detected values of the reactor current IL, the primary winding current Iac and the voltage Vac are input to the control device 20.
- the voltage detector 18 corresponds to an embodiment of the "voltage detector”.
- the control device 20 generates control signals G1 to G4 for controlling the on / off of the semiconductor switching elements Q1 to Q4 by using the detected values of the primary winding current Iac, the reactor current IL, and the voltage Vac.
- control configuration of the power conversion device 100 shown in FIG. 1 will be described.
- control configuration of the power conversion device according to the comparative example will be described.
- FIG. 2 is a functional block diagram illustrating a control configuration of the power conversion device according to the comparative example.
- the control device 200 of the power conversion device according to the comparative example includes a voltage control unit 300, a current control unit 50, and a PMW circuit 60.
- the voltage control unit 300 includes a subtractor 32, a voltage controller 34, adders 36 and 38, and a gain calculator 40.
- the subtractor 32 calculates the deviation ⁇ Vac of the voltage Vac detected by the voltage detector 18 with respect to the voltage command value Vac * of the capacitor C1.
- the voltage command value Vac * is set to a sinusoidal voltage of a desired frequency (for example, a commercial frequency).
- the voltage command value Vac * corresponds to the "AC voltage command value".
- the voltage controller 34 generates an inverter control command value by a control operation for reducing the deviation ⁇ Vac calculated by the subtractor 32.
- the inverter control command value corresponds to the command value of the alternating current output from the alternating current side of the inverter 10.
- the gain G1 indicates the gain of the control operation in the voltage controller 34.
- the voltage controller 34 has a proportional term (Kp ⁇ ⁇ Vac) obtained by multiplying the deviation ⁇ Vac by the proportional gain Kp and an integral term (Ki ⁇ ⁇ ( ⁇ Vac)) obtained by multiplying the integral value of the deviation ⁇ Vac and the integral gain Ki.
- the inverter control command value can be obtained by the feedback calculation that adds and.
- the adder 36 adds the primary winding current Iac detected by the current detector 16 to the inverter control command value as a feedforward term. By adding the feedforward term to the feedback calculation result, the current control system can follow a sudden change in the primary winding current Iac at high speed.
- the gain calculator 40 multiplies the voltage Vac detected by the voltage detector 18 with the reciprocal (1 / G2) of the gain G2 of the current controller 54.
- the adder 38 generates a reactor current command value IL * by adding the output (Vac / G2) of the gain calculator 40 to the output of the adder 36 for voltage compensation.
- the reactor current command value IL * corresponds to the "alternating current command value".
- the current control unit 50 includes a subtractor 52 and a current controller 54.
- the subtractor 52 calculates the deviation ⁇ IL of the reactor current IL detected by the current detector 14 with respect to the reactor current command value IL *.
- the current controller 54 generates an inverter control command value Vinv * by a control operation for reducing the deviation ⁇ IL calculated by the subtractor 52.
- the inverter control command value Vinv * corresponds to the command value of the output voltage Vinv of the inverter 10.
- the gain G2 indicates the gain of the control operation in the current controller 54.
- the current controller 54 has a proportional term (Kp ⁇ ⁇ IL) obtained by multiplying the deviation ⁇ IL by the proportional gain Kp and an integral term (Ki ⁇ ⁇ ( ⁇ IL)) obtained by multiplying the integral value of the deviation ⁇ IL and the integral gain Ki.
- the inverter control command value Viv * can be obtained by the feedback calculation that adds and. With the periodic change of the reactor current command value IL *, the inverter control command value Vinv * also becomes an AC waveform of the same frequency.
- the PWM circuit 60 generates control signals G1 to G4 for controlling the inverter output voltage Vinv to the inverter control command value Vinv *. Specifically, the PWM circuit 60 generates PWM signals S1 and S2 according to a voltage comparison between the inverter control command value Vinv * and the carrier wave. Basically, during the period when Vinv * is lower than the voltage of the carrier wave, the PWM signal S1 is set to the H level, while the PWM signal S2 is set to the L level. On the other hand, in the period when Vinv * is higher than the voltage of the carrier wave, the PWM signal S1 is set to the L level, while the PWM signal S2 is set to the H level.
- control signals G1 and G4 are set to the H level in order to turn on the semiconductor switching elements Q1 and Q4.
- the control signals G1 and G4 are set to the L level in order to turn off the semiconductor switching elements Q1 and Q4.
- the control signals G2 and G3 are set to the H level in order to turn on the semiconductor switching elements Q2 and Q3.
- the control signals G2 and G3 are set to the L level in order to turn off the semiconductor switching elements Q2 and Q3.
- a dead time is provided between the PWM signals S1 and S2.
- the transformer 3 when the power converter 100 is connected to the transformer 3 by turning on both the circuit breakers 2a and 2b, the transformer 3 is excited depending on the phase of the voltage Vac at the time of connection. Inrush current may occur.
- the exciting inrush current causes a transient fluctuation in the voltage supplied to the load 4, and may cause the load 4 to malfunction.
- a magnetic flux is generated in the iron core 3c of the transformer 3.
- the waveform of the voltage Vac is an ideal sine wave
- the magnetic flux is a sine wave 90 degrees behind the voltage Vac.
- the circuit breakers 2a and 2b are closed at the position where the voltage Vac becomes 0, the magnetic flux reaches the maximum value.
- the magnetic flux remains in the iron core 3c of the transformer 3, the magnetic flux becomes a sine wave with the residual magnetic flux as the initial value.
- the fact that the residual magnetic flux is generated in the iron core 3c of the transformer 3 indicates that the DC component is superimposed on the magnetic flux density of the iron core 3c (hereinafter, also referred to as “DC demagnetization”). There is.
- the voltage control unit 300 adds the primary winding current Iac detected by the current detector 16 as a feedforward term to the feedback calculation result. Therefore, when the exciting inrush current is generated, the primary winding current Iac changes suddenly, so that the current control unit 50 follows the sudden change of the primary winding current Iac at high speed. As a result, there is a concern that the exciting current will increase, resulting in an increase in DC demagnetization.
- a demagnetization detection circuit is used to detect a DC component included in the output voltage of the inverter, and the detected DC component is used.
- a configuration is disclosed in which the waveform of the output voltage of the inverter is controlled so as to be eliminated.
- This demagnetization detection circuit has an integrator that integrates the output voltage of the inverter, and is configured to detect the DC component of the output signal of the integrator.
- the demagnetization detection circuit described in Patent Document 1 is configured to detect the DC demagnetization of the iron core 3c of the transformer 3 based on the output signal of the integrator and control the inverter. It is difficult to quickly suppress the exciting inrush current.
- the control device 20 when the control device 20 detects the excitation inrush current included in the primary winding current Iac, the magnitude of the feed forward term in the voltage control unit is reduced. It is configured to let you.
- FIG. 3 is a functional block diagram illustrating an example of the control configuration of the power conversion device 100 according to the present embodiment.
- Each functional block constituting the control device 20 is realized by, for example, software processing and / or hardware processing by the microcomputer constituting the control device 20.
- the control device 20 includes a voltage control unit 30, a current control unit 50, and a PWM circuit 60.
- the control device 20 shown in FIG. 3 is different from the control device 200 according to the comparative example shown in FIG. 2 in that it has a voltage control unit 30 instead of the voltage control unit 300.
- the voltage control unit 30 includes a subtractor 32, a voltage controller 34, adders 36 and 38, gain calculators 40 and 42, and a demagnetization suppression unit 44.
- the voltage control unit 30 is a voltage control unit 300 shown in FIG. 2 with a gain calculator 42 and a demagnetization suppression unit 44 added.
- the gain calculator 42 multiplies the primary winding current Iac detected by the current detector 16 and the gain G3, and outputs the multiplication result to the adder 36.
- the adder 36 adds the output (Iac ⁇ G3) of the gain calculator 42 to the inverter control command value generated by the voltage controller 34 as a feedforward term.
- the gain G3 is a gain for adjusting the magnitude of the feedforward term, and can take a value larger than 0 and 1.0 or less.
- the feedforward term becomes the primary winding current Iac itself, which is equal to the feedforward term in the comparative example of FIG.
- the demagnetization suppression unit 44 sets the value of the gain G3 used in the gain calculator 42 based on the primary winding current Iac detected by the current detector 16. As described below, the demagnetization suppressing unit 44 sets the gain G3 to a value of less than 1.0 when the exciting inrush current superimposed on the primary winding current Iac is detected. ,
- the feedforward term is configured to be small.
- FIG. 4 is a functional block diagram showing the configuration of the demagnetization suppressing unit 44 shown in FIG.
- the demagnetization suppression unit 44 includes a detection unit 70, a determination unit 80, and a setting unit 90.
- the detection unit 70 extracts the exciting current superimposed on the primary winding current Iac detected by the current detector 16.
- the determination unit 80 determines the presence or absence of an exciting inrush current based on the magnitude of the exciting current extracted by the detection unit 70.
- the determination unit 80 determines that the detection value of the primary winding current Iac has the excitation inrush current
- the determination unit 80 outputs a signal DET activated to the H level as a signal indicating the determination result. ..
- the H-level signal DET indicates that DC demagnetization is occurring in the transformer 3.
- the determination unit 80 determines that the detected value of the primary winding current Iac does not have the excitation inrush current, uses the signal DET deactivated to the L level as a signal indicating the determination result. Is output.
- the L-level signal DET indicates that no DC demagnetization has occurred in the transformer 3.
- the setting unit 90 sets the value of the gain G3 according to the output signal DET of the determination unit 80.
- the setting unit 90 receives the L level signal DET
- the predetermined value K is a value greater than 0 and less than 1.0 (0 ⁇ K ⁇ 1.0).
- the setting unit 90 outputs the set gain G3 to the gain calculator 42.
- the gain calculator 42 multiplies the primary winding current Iac detected by the current detector 16 with the gain G3.
- FIG. 5 is a circuit diagram showing a configuration example of the demagnetization suppressing unit 44 shown in FIG.
- the detection unit 70 has a low-pass filter (LPF) 72.
- the LPF 72 is configured to prevent the current IL of a desired frequency (for example, a commercial frequency) output from the output filter 12 from passing through, and to pass an exciting current having a frequency lower than the desired frequency. That is, the LPF 72 extracts the exciting current from the primary winding current Iac detected by the current detector 16.
- a desired frequency for example, a commercial frequency
- the determination unit 80 has an absolute value circuit (ABS) 82, a threshold value 84, and a comparator 86.
- the absolute value circuit 82 calculates the absolute value of the exciting current and outputs a signal indicating the calculation result.
- the comparator 86 compares the output signal of the absolute value circuit 82 with the preset threshold value 84, and outputs a signal indicating the comparison result.
- the threshold value 84 is set assuming an exciting inrush current that flows in the primary winding 3a when magnetic saturation occurs in the iron core 3c of the transformer 3.
- the comparator 86 outputs the H level signal DET.
- the comparator 86 outputs the L level signal DET.
- the setting unit 90 has a switching unit 92.
- the switching unit 92 has a first input terminal, a second input terminal, and an output terminal.
- the first input terminal receives a predetermined value K
- the second input terminal receives a value "1.0".
- the predetermined value K is a value greater than 0 and less than 1.0 (0 ⁇ K ⁇ 1.0).
- the switching unit 92 selects one of the two input values based on the output signal DET of the comparator 86, and outputs the selected value as the gain G3 from the output terminal. Specifically, when the output signal DET of the comparator 86 is H level, the switching unit 92 selects a predetermined value K. On the other hand, when the output signal DET of the comparator 86 is L level, the switching unit 92 selects the value "1.0".
- the gain calculator 42 outputs a value obtained by multiplying the detected value of the primary winding current Iac by a predetermined value K, that is, a value obtained by reducing the primary winding current Iac, as a feedforward term. According to this, when the power converter 100 is connected to the transformer 3 and a DC demagnetization occurs in the transformer 3, the feedforward term in the voltage control unit 30 becomes small.
- the gain calculator 42 outputs the detected value of the primary winding current Iac by the current detector 16 as a feedforward term. According to this, since the feedforward term in the voltage control unit 30 is maintained, the responsiveness of the current control system to a sudden change in the primary winding current Iac can be ensured.
- the control device 20 further includes a demagnetization detection unit 64 and a correction unit 62.
- the demagnetization detection unit 64 has the same function as the demagnetization detection circuit described in Patent Document 2. Specifically, the demagnetization detection unit 64 detects the DC component Vdc of the signal indicating the magnetic flux generated in the iron core 3c of the transformer 3 based on the voltage Vac detected by the voltage detector 18.
- the correction unit 62 corrects the inverter control command value Vinv * by adding a DC offset value to the inverter control command value Vinv * so as to eliminate the DC component Vdc detected by the demagnetization detection unit 64.
- the PWM circuit 60 generates control signals G1 to G4 by comparing the inverter control command value Vinv * corrected by the correction unit 62 with the carrier wave.
- the demagnetization detecting unit 64 subsequently suppresses the generation of DC demagnetization. .. Therefore, even if the feedforward term is returned to the original size after the power conversion device 100 is connected in the demagnetization suppression unit 44, DC demagnetization does not occur. As a result, the DC demagnetization of the transformer 3 can be converged without affecting the control in the steady state.
- FIG. 6 is a circuit diagram showing another configuration example of the demagnetization suppression unit 44 shown in FIG.
- the demagnetization suppressing unit 44 has a different configuration of the setting unit 90 as compared with the demagnetizing suppressing unit 44 shown in FIG.
- the setting unit 90 of this modification example is a setting unit shown in FIG. 5 with a limiter 94 added.
- the limiter 94 is provided between the switching unit 92 and the gain calculator 42.
- the limiter 94 is used when the value of the gain G3 is switched from “1.0" to the predetermined value K by the switching unit 92, or when the value of the gain G3 is switched from the predetermined value K to "1.0". , It is configured to limit the rate of change of the gain G3.
- the rate of change of the gain G3 corresponds to the amount of change of the gain G3 per unit time.
- the predetermined rate of change is set according to the control response in the current control unit 50. According to this, when the value of the gain G3 is switched, the value of the gain G3 changes according to a predetermined rate of change, so that the control stability in the current control unit 50 is ensured.
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Abstract
Description
図1を参照して、実施の形態に係る電力変換装置100の直流側には、直流電源1が接続される。電力変換装置100の交流側には、遮断器2a,2bおよび変圧器3を介して負荷4が接続される。変圧器3は、1次巻線3a、2次巻線3bおよび環状の鉄心3cを有する。
図2を参照して、比較例に係る電力変換装置の制御装置200は、電圧制御部300と、電流制御部50と、PMW回路60とを含む。
図5を参照して、検出部70は、低域通過フィルタ(LPF)72を有する。LPF72は、出力フィルタ12から出力される所望の周波数(例えば商用周波数)の電流ILが通過することを防止し、所望の周波数よりも低い周波数の励磁電流を通過させるように構成される。すなわち、LPF72は、電流検出器16により検出された1次巻線電流Iacから、励磁電流を抽出する。
上述した実施の形態では、電流制御部50におけるフィードフォワード項の大きさを決めるゲインG3の値を、「1.0」および所定値Kの間で切り替える構成例について説明した。この構成例では、フィードフォワード項の大きさが変化する際に制御安定性が低下する可能性が懸念される。
Claims (5)
- 直流側の直流電圧を交流電圧に変換して交流側に出力するインバータと、
前記インバータを制御する制御装置とを備え、
前記インバータの前記交流側は変圧器を介して負荷に接続され、前記変圧器は、前記交流側から出力される前記交流電圧を前記負荷に与えるように構成され、
前記変圧器の1次巻線電流を検出する第1の電流検出器と、
前記インバータの出力電流を検出する第2の電流検出器と、
前記交流側から出力される交流電圧を検出する電圧検出器とをさらに備え、
前記制御装置は、
交流電圧指令値に対する前記電圧検出器による前記交流電圧の検出値の偏差を小さくするための制御演算結果に、前記第1の電流検出器による前記1次巻線電流の検出値にゲインを乗算したフィードフォワード項を加算することによって、交流電流指令値を生成する電圧制御部と、
前記交流電流指令値に対する前記第2の電流検出器による前記インバータの出力電流の検出値の偏差を小さくするための制御演算によって、インバータ制御指令値を生成する電流制御部と、
前記インバータ制御指令値と所定の搬送波とを比較して前記インバータの制御信号を生成することにより、前記インバータをPWM制御するPWM回路とを含み、
前記電圧制御部は、前記第1の電流検出器による前記1次巻線電流の検出値に励磁突入電流が検出されたときには、前記励磁突入電流が検出されないときに比べて、前記ゲインの値を小さくする、電力変換装置。 - 前記電圧制御部は、
前記第1の電流検出器による前記1次巻線電流の検出値における前記励磁突入電流の有無を検出し、
前記1次巻線電流の検出値が前記励磁突入電流を有するときには前記ゲインの値を第1の値に設定し、前記1次巻線電流の検出値が前記励磁突入電流を有しないときには前記ゲインを前記第1の値よりも小さい第2の値に設定する、請求項1に記載の電力変換装置。 - 前記第1の値は1.0であり、
前記第2の値は0より大きく1.0未満である、請求項2に記載の電力変換装置。 - 前記電圧制御部は、前記ゲインの切替時における前記フィードフォワード項の変化率を制限するためのリミッタを有する、請求項1から3のいずれか1項に記載の電力変換装置。
- 前記制御装置は、
前記電圧検出器による前記交流電圧の検出値に基づいて、前記変圧器の鉄心に発生する磁束を示す信号の直流成分を検出する偏磁検出部と、
前記直流成分をなくすように前記インバータ制御指令値を補正する補正部とをさらに含み、
前記PWM回路は、前記補正部により補正された前記インバータ制御指令値と前記所定の搬送波とを比較して前記インバータの制御信号を生成する、請求項1から4のいずれか1項に記載の電力変換装置。
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